Not really a "proof of concept", but an interesting demo of a way of doing Cut/Copy/Paste.
Hopefully, Apple will get off their backsides and get this little missing feature into the iPhone. It's pretty much the top missing feature for me. Not being able to "edit" text I'm writing really makes using the iPhone for email pretty close to impossible.

Dude, the video is a "suggestion" of what copy and paste would be like if the guy could actually put the code into the phone. It's not actually there. It's a lot of Photoshop/Final Cut Pro magic. (Assuming he used a Mac to do the video editing)
I guess it's a testament of how well the video was put together that you felt that he was describing how to do copy and paste, not how it "should" or "could" be done. :)